Process of preparing butadiene



Patented Oct. 7, 1930 UNITED STATES ,PATEN'D OFFICE ELHEIB, K. BOLTON, OF WILMINGTON, DELAWARE, AND FREDERICK B. DOWNING, OI

CABNEYS POINT, NEW JERSEY, ASBIGNORS TO E. I. DU FONT-DE NEHOUBS & GOI- PANY, OI WILMINGTON, DELAWARE. A CORPORATION 01 DELAWARE rnoc'ass or rnaranme nu'ranmna 80 Drawing.

This invention relates to the production of butadiene GH =CH f CH= CH from diacetylene, HEC CECH, and, more particularly, by the catalytic hydrogenation of the diacetylene. I

- Various methods have been suggested for the preparation of butadiene, but many of.

them have been found objectionable for various reasons and are of small value since they are not adapted for commercial utilization. Furthermore, the methods of the prior art generally require the use of high temperatures, which make the processes not only uneconomical but ineflicient, due, in a large measure, to the undesirable products of decomposition which are formed in substantial quantities when high temperatures are used.

It. is one of the objects of this invention to ,prepare butadiene by means of a comparaylene and hydrogen is passed over a suitable catalyst which is preferably maintained at ordinary or slightly elevated temperatures, the hydrogen is caused to combine with the diacetylene in such proportions as to yield butadlene.

'More specifically, butadiene is prepared by the rocedure described in detail below. 'A' cata yst is prepared by igniting purified nickel nitrate, gently at first, and finally to a tem erature of 350400 C. until all nitrogen oxi es are driven off. Heating the material to redness is to be avoided as well as any unnecessaryignition after the oxides of nitrogen have been removed, since the rate of subsquent reduction of the nickel is retarded and the activity of the catalyst is impaired by excessive heating.' The ignited nickel oxide is reduced in a stream of pu'rified hydrogen at a temperature of approximately 300 C. The

Application filed January 8, 1927. Serial No. 159,903.

finely divided nickel thus reduced is cooled, preferably in a stream of ydrogen or other non-oxidizing gas, and is then ready for use.

A'suitable quantit of the nickel catalyst is placed in any suita 11': contact apparatus, and, while maintaining the catalyst at a temperature between 40 and 80 C.,-the reaction gas mixture is contacted therewith. Such gas mixture contains hydrogen and diacetylene in about the proportions o 2: 1, and its passage through the contact apparatus is governed by an analysis of the emergent ases, care being taken to control the rate of low toobtain the best conversion. The hydrogen and diacetylene combine to form the butadiene which may be recovered from the eflluent gases by any desired method.

Since butadiene condenses to a liquid at about. 0 0., it may be separated by chilling theeflluent gases to a temperature of or below 0 C. If any of the other constituents of thegases are condensed with the buta diene, the latter may be separated from them in any suitable manner. Or, if desired, the

'butadiene resulting from the reaction may be recovered by treating the gaseous or liquefied reaction products with an a ueous or acid solution of sulfur dioxide. he crystalline compound thus formed may then be isolated or decom osed with the production of butadiene of 'gh purity.

. It isevident that many variations may be introduced in the process withoutmaterially afiecting the results. The number of hydrogenating catalysts which are suitable for use in the process is large,and includes such active metal catalysts as nickel, platinum, alladium copper, orniixtur es thereof. e catalytic contact masses may be prepared in any suitable 'way, and maybe used alone, or supported on, or mixed with inert materials. Suitable promoters may be. added to the catalystrmasses for enhancing the catalytic properties of such masses. The catalyst is pref Verably in finely divided form.

I Theca'ta-lytic hydrogenation may be carriedput at various ressures and temperatures. *Itha's been ound that excellent results are'obtained by maintaining the pressure of the reactionjsystem at, or slightly 7 results are hydrogen are present in the proportion of which comprises passlng a gas containing sons and other deleterious sirable reactionand decomposition-products with corresponding decreases in the yield of 1 butadiene. I

The gas mixtures containing diacetylene and hydrogen may be varied largely as to proportions but it has been found that good obtained when the diacetylene and about 1:2, corresponding to the equation C H +2H .=C H 'It is usually preferable to use somewhat less hydrogen than the theoretical, in preference to using an excess of which comprises passing a gas containing,

diacetylene and hydrogen in proportions not substantially in excess of 1 :2 over a hydrogenating metal catalyst at a temperature between 40 to 80 C.

6. The process of producing butadiene which comprises passing a gas containing diacetylene and hydrogen in proportions not substantially in excess of 1 2 over a finely divided nickel catalyst at a temperature between 4;080 G. I

In testimony whereof we aflix our signatures.

' .ELMER- K. BOLTON.

FREDERICK B. DOWNING.

hydrogen. It is sometimes desirable to use hydrogen and diacetylene in proportions of less than 2: 1-to avoid partial overreduction and loss of valuable hydrocarbons, and to finish the reduction in some other manner. The gas mixtures may also contain saturated hydrocarbons, nitrogen, or other inert gases.

The mixtures may be dried and purified rior .to the reaction, suitable precautions ing taken, when necessary, to avoid catalyst poisubstances in the gas mixtures.

The butadiene prepared according to the present process is capable of utilization in any of the well-known ways, and is particularly valuable for use in the manufacture of synthetic rubbers. The present process is well adapted for commercial application, and is highly valuable for this reason.

' Any suitable apparatus may be used in carrying out the present process, the details of such apparatus being readily apparent to those skilled in the art. 4 Suitable changes may be made in the details of the process without departing from the spirit or scope of the present invention.

We claim:

1. The process of preparing butadiene diacetylene and hydrogen over a'nickel catalyst at a temperature between 4080 C.

2. The process of preparing butadiene' which comprises passing a gas containing diacetylene and hydrogen in proportions not in excessof 1:2 over a nickel catalyst at a temperature between 0400 C.

3. The process of producing butadiene which comprises passing a gas containing diacetylene and hydrogen in substantially the proportions of,1 :2 over a catalyst adapt ed to promotethe hydrogenation of the diacetylene.

4'. The process of producmg butadiene 

